Automatic change-over



y 1937- A. v. MULLEN ET AL 2,081,015

AUTOMATIC CHANG E OVER Filed May 10, 1934 2 Sheets-Sheet l BB. 1INVENTORS.

ANDREW K/Vw. 4 EM BY 5 JOHN C SM/7H.-

ATTORNEYS.

May 18, 1937. A. v. MULLEN ET AL AUTOMATIC CHANGE-OVER 2 Sheets-Sheet 2l l l 1 l I I l 4 I l I I l I i I Filed May 1 0, 1954 INVENTORS.

ANDREW V/VUL L /v.

5 Jo/7w C SM/ TH. M P M ATTORNEYS,

Patented May 18 1937 UNITED STATES PATENT OFFICE AUTOMATIC CHANGE-OVERApplication May 10, 1934, Serial No. 724,926

6 Claims.

Our invention relates to change-overs for use with two moving pictureprojectors using sound film, when showing a film in a moving picturetheatre or other appropriate place. It is the usual procedure whenshowing moving pictures comprising more than one reel, to use twomachines. One machine is loaded with the first reel, and the othermachine with the succeeding reel. When the first reel has been shown,the first machine is stopped and the second machine is started. In orderto accomplish this so that there is no apparent pause or break in thesequence, this change-over must be made very quickly and at the correctinstant. The fact that the modern moving picture film also carries asound track on the edge of the film greatly complicates this procedure,since the changeover must be made of both the picture and the sound atthe same instant so that there is no apparent pause or delay in thecontinuity of the sound, as well as the picture, and so that there is noextraneous noise in the operation of changing over. The method of makingthis change heretofore has been for the operator to get the secondmachine in readiness, and then when the first machine has reached theend of the film it is showing, to quickly douse the light on the firstmachine and open the douser on the secon-d machine, and at the same timeto disconnect the loud speaker from the first machine and connect it tothe second machine. This, of course, being done by hand, necessitated arather apparent delay in the continuity, and especially so in the soundprojection. Another difiiculty en countered in the use of sound film isthat the sound projected into the auditorium is produced in mostinstances by the use of a photo-electric cell which is energized bylight shining through a sound track in the side of the film. In somefilms the sound track is more opaque than in others, and therefore doesnot permit the same amount of light to shine through onto thephotoelectric cell.

In other instances the light source of one machine is brighter than thelight source on the other machine, due to the use of a new photoelectriccell or to numerous other causes. Inasmuch as the volume of the soundprojected into the auditorium is determined by the brightness of thelight shining on the photo-electric cell, a change over from one machineto the other carrying a film of equal density, under these conditions,often causes a decided change in the volume of the sound. This is, ofcourse, very objectionable, and in order to avoid this change in volumeadjustable potentiometers are placed between the output leads of thephoto-electric cells and the amplifiers which operate the speaker unitof the apparatus. The apparatus for adjusting the volume and tone of therespective machines, as determined by the amount of light shiningthrough the film on the cell, is called a fader. There are numerousfaders on the market which in most cases comprise the two potentiometersas described above. These potentiometers are calibrated so that when thechange-over is made from a film of one density to another, thepotentiometer setting on the machine which carries the new film may bemade before the change-over. The operator knows the general setting onthe fader for the different types of commercial film; and if themachines are in balance as regards the intensity of the light sourceshining on the photo-electric cell, he may set the iader before thechange-over and thus obviate any change in volume of the sound when theactual change-over is made. However, as heretofore stated, one machinemay have a new photo-electric cell, while the other machine has an oldcell which is not so sensi- 2 tive to light; therefore the setting onthe fader will be changed and the calibrations thrown out. This is adecided disadvantage, and the only thing that the operator has been ableto do heretofore was to make his change-over as best he could and thenadjust his fader by car so that the sound would be adjusted to the givenvolume.

In order for an operator to make a changeover in the old manner it wasnecessary for him to shut off the light from the first projector byplacing a screen between the light and the projection screen. It is notpossible to merely turn off the light in one projector, since the lightis usually furnished by a carbon arc, and the turning off of theelectricity does not at once cut off the light since the hot carbonscontinue to glow. Therefore the operator uses what is called a douser,which is in reality an opaque screen which he places over the front endof the lamp house. This douser is also used to start the second machinein regard to projecting the beam of light, since carbon lights must bestarted and allowed to burn a short time in order to heat up thecarbons.

From the above, it may be seen that the average moving picture operator,when making a change-over, must douse the light of the first machine andat the same time remove the douser from the second machine. While doingthis he must at the same time change over the sound projection bybreaking the connection from the first photo-electric cell and thespeaker and connecting the second photo-electric cell to the samespeaker, and at the same time adjust the fader. In order to get smoothaction and smooth sound this must be all done at one and the same time.

It is an object of our invention to provide a set up which will permitthe operator to press one button, which will automatically andcompletely change over both the moving projection and the soundprojection at one and the same time.

It is an object of our invention to accomplish the above without anyappreciable stop or pause between the showing of each succeeding film,so that to the audience it will appear and sound like one continuousfilm with nothing whatever to indicate to them that a change-over isbeing or has been made.

Another object of our invention is to provide a means whereby thechanging of the contacts from the outlet of one photo-electric cell toanother all will be accomplished without the usual click or noiseincident to throwing the switch.

A further object of our invention is to provide means which willeliminate the usual complicated adjustment of the fader in devices ofthis kind, and substitute for this adjustment a very simple device whichwill accomplish the same purpose, and which is very much more flexiblein its control.

A still further object of our invention is to provide means which willautomatically change over the projection of both the pictures and thesound from one machine to the other without the necessity of any manuallabor or action at all, thereby making the change-over truly automatic.

These and other objects of our invention which will be set forthhereinafter or will be apparent to one skilled in the art upon readingthese specifications, we accomplish by that certain construction andarrangement of parts of which We shall now describe a preferredembodiment. Reference is now made to the drawings which form a parthereof, and in which:

Figure l is a schematic diagram of the set up and the wiring of ourinvention.

Fig. 2 is a front elevation of our douser.

Fig. 3 is an end view of our douser as illustrated in Fig. 2.

Fig. 4 is a front elevation of our novel sound change-over.

Fig. 5 is a plan view of our sound change-over illustrated in Fig. 4.

Fig. 6 is a portion of the armature used in our novel sound change-over.

Generally, our invention comprises three parts: An electrically operateddouser on the lamp house of each machine, an electrically operatedchangeover for the sound, and means for operating the two at one and thesame time. The douser is operated by the use of electric solenoidsacting upon a common armature, and the sound changeover, which inreality is in its simplest aspect a double throw single pole switch, isalso actuated by solenoids having a common armature. Placed in thecircuit from each of the photo-electric cells and the contacts on thesound change-over are two potentiometers; that is, one in each circuit.These potentiometers are used merely to balance the output from thephoto-electric cells as determined by their efficiency to the exciterlight. By adjusting these potentiometers it is possible to balance thetwo machines so that when the same type of film is run through them itwill not be necessary to adjust the fader at all, and the only time thefader needs adjustment is when changing from one type of film toanother. This permits the using of only one side or one of thepotentiometers in the iader itself, since the compensation for theefliciency of the photo-electric cell is made in the potentiometers inthe sound change-over. The means for operating the douser and the soundchange-over together is by the completion of electric circuits, whichmay be done manually by the use of push buttons, or by means actuated bythe film itself as it runs through the machine.

Briefly, we provide a douser as shown in Fig. 2, and generally shown byI and l in Fig. 1. The douser consists of a supporting frame 2, on thetop of which are mounted two solenoids 3 and 4. The frame 2 has a cutout portion 5 to permit the light from the lamp house to shine throughand upon the aperture plate of the projector. The cores of the solenoids3 and 4 are in a horizontal position and are in line with each other.There is an armature 6 common to both solenoids and journaled in theircore. The douser screen I itself is attached to the armature 6 by meansof a. projecting arm 8 journaled in the armature 6 and fastened to thedouser screen I by means of a bracket 9, or by any other convenientmeans. The douser screen I rides horizontally in tracks 10 formed in theframe portion 2, and there are stops 2a on the frame to insure thecorrect positioning of the screen. The arm 8 may be carried up throughthe armature 6 a short way and mounted with a nob l I which acts as ahandle to manually actuate the douser screen. The douser frame ismounted on the housing 12 of the lamp house by brackets l3 and in such amanner that the light from the machine will shine through the cut outportion 5. It is now apparent that if the solenoid 3 is energized itwill pull the armature 6 within its core and thus draw the douser screen1 over the cut out portion 5, until it hits the stop and prevents thelight from the machine shining on the moving picture screen. If, on theother hand, solenoid 4 is energized it will act to draw the douserscreen 1 away from the aperture 5 and thus permit the light from theprojector to shine on the screen.

We will now describe our preferred sound change-over which isillustrated in Fig. 4, and generally shown at H in Fig. 1. Mounted on anon-conductive panel l5 are two solenoids l6 and I! which are placedwith their cores in a horizontal position and in line with each other.ably journaled within these two cores is an armture [8, common to bothsolenoids and carrying at its mid point a non-conductive collar I9.Mounted on the panel I5, above the solenoids, are two flat springs and2|, wound in a spiral with flat ends, which are fastened to the panel bymeans of conductive posts 22 and 23 in such a way that the flat ends ofthe springs are urged against contacts 24 and 25. The ends of thesprings 20 and 2| at their flattened portion contain a slight bulge.These springs 20 and 21 are mounted in such a manner above the solenoidsl6 and I1 that the collar 19 will lift the ends of the springs from thecontacts 24 and 25 when the armature I8 is at its limit to the right orto the left. The conductive posts 22 and 23, on which the springsaremounted, are connected to a common terminal 26, which in turn isconnected to the main amplifiers of the speaker. The contacts 24 and 25are connected through the po- Slidtentiometers21 and 28 to terminals 29and 30, which are connected to the out-put of the two photo-electriccells, as will be described later. One end of the windings on thesolenoids I6 and H are connected to a common terminal 3|, and the otherends to terminals 32 and 33. There is a ground terminal 34, which inturn is connected to the two terminals 24 and 25 through grid leaks 35and 36. It is now apparent that if solenoid I6 is energized, thearmature I6 will be pulled over to the left, the position shown in Fig.4, and the collar I9 will lift the end of the spring 20 from the contact24, and thus break the connection between the terminal 29 and theamplifier terminal 26; The bulged portion 26a will maintain the armaturein the position shown in Fig. 4 until solenoid I1 is energized, at whichtime the armature I8 will be pulled over to the right and the spring 20will contact the contact terminal 24, and there will be a closed circuitbetween terminal 29 and 26. At the same time the collar I9 will liftspring end 2I from the contact 25, and the connection between terminal30 and the terminal 26 will be broken. The grid leaks and 36 are a veryimportant part of our invention, since it has been found that theyentirely eliminate any click or noise in the speaker when theconnections are made or broken when the change-over of the sound ismade.

We will now describe the wiring of our invention and explain itsoperation.

As has been heretofore stated, a douser is mounted on the front portionof each of the two lamp houses. In Fig. 1, we have indicated generallythe two dousers I and I. I represents the douser on the first machine,or the machine which is about to run out of film, while I represents thedouser on the second or succeeding machine, which is to be started upwhen the first machine has completed its film, and then carry on boththe picture and the sound. The solenoids of the dousers are so woundthat when one of them is energized it will pull the armature 6 into thecore, which in turn will pull the douser screen I toward the energizedsolenoid. In Fig. 1 the dousers are so depicted that the screens I willcover the openings 5 when the screens I are to the right, and will leavea clear opening for the light from the lamp house when the screens areto the left. One end of the windings of solenoids 3 and 4 are connectedtogether in each of the dousers, and in turn these are connected by wire31 with each other. The other end of the winding of solenoid 3, indouser I, is connected to the other end of the winding 4, in douser I,by wire 39. Positioned near each machine is a bank of push buttonscomprising two buttons 42 and 43 near machine I, and buttons 42' and 43near machine I. Pressing these buttons depresses a contact, which inturn contacts a plate 44 common to each set of two buttons. The plates44 and 44 are connected together by the wire 45. Lead wires 46 and 4'!from a source of either A. C. or D. C. electricity are connected to thewires 31 and 45. The contact from button 43 on douser I is connected bywire 48 to Wire 36, while the contact under button 42' of douser I isalso connected by wire 49 to wire 38. The contact under button 42 of thesecond machine, and button 43 of the first machine are both connected towire 39, by wires 50 and 5I, respectively. It is now apparent that ifbutton 42 or button 43 is depressed, the douser screen I in douser Iwill slide to the left, and at the same time the screen I in douser Iwill slide to the right. Thus the light from the second machine will bepermitted to shine on the screen and the light from the first machinewill be blocked out. If, on the other hand, button 42 or 43 is pushed,the reverse will happen, and the light from the first projector willshine on the moving picture screen and the light from the secondprojector will be blocked out.

We have shown a manner in which our circuits for changing over may beaccomplished automatically. Over the supply reel or top magazine on eachmachine is a vertical bar 60, which rides on top of the film 6I in thereel 62. As the film 6I is used up, the bar rides down on the film withthe diminishing of the diameter of the roll of film. There is aprojection or arm 63 on the bar 66 which actuates a switch 64 when thefilm has almost reached the end and the bar has consequently lowered tothe necessary point. The switch 64 on the first machine closes a circuit65, connecting the lead wire 41 and the wire 39, which is a shunt aroundthe button 43'. This acts just the same as if the button 43' or 42 werepushed and the light from the first machine is blocked oiT and the lightfrom the second machine allowed to shine on the moving picture screen.The switch 64 on the second machine closes a circuit 66 between the leadline 41 and the wire 38, which shunts around the button 43. Thisreverses the process just as if the button 43 or 42 had been depressed.There are a number of ways in which the film itself may be made toactuate these switches, and we have described one method as merelyillustrative. We do not intend to limit ourselves to this exactconstruction shown in this application, since there are numerous waysknown in the art for accomplishing this purpose.

The sound change-over is connected in this circuit in the followingmanner: The terminal 3|, which is common to both of the solenoids I6 andI1, is connected by wire 68 to the wire 46, which is one of the leadsfrom the source of electricity. The other end of the winding of solenoidI6 is connected by wire 69 to the push button circuit 43 and contact 43.The other end of the winding of solenoid I1 is connected by wire I6 tothe contact of push button 43. Thus it is apparent that when the pushbuttons are actuated to douse the light of the first projector, thesolenoid I'I on the sound change-over will be energized and the armatureI8 will move to the right, thus lifting the contact spring 2I off of thecontact 25, and permitting contact spring 20 to contact terminal 24.tons are actuated to douse the light in the succeeding projector, thesolenoid I6 will be energized and the contact between the spring 20 andthe terminal 24 will be broken, and the contact between spring 2I andterminal 25 made. The terminal 30, which is connected to the terminal 25through the potentiometer 28, is connected by the wire I2 to the outputterminal of the photoelec tric cell II, which is located in the firstmachine. The terminal 29, on the other side of the sound change-over, isconnected by wire I3 to the output terminal of the photo-electric cellII, which is located in the succeeding machine. The terminal 34, whichruns from the two grid leaks 35 and 36, is grounded by means of wire I4.The terminal 26, which is connected to the two springs 26 and 2|, runsto the head amplifier, fader, or main amplifiers of the speaker. It istherefore apparent that when the light projected from the machines ischanged over from one machine to If, on the other hand, the push buttheother, that at the same time the sound is changed over by connecting thedifferent photoelectric cells in the difierent machines to theamplifiers of the speaker. The grid leaks 35 and 35, in series betweenthe circuits and the ground, entirely eliminate any click or foreignsound being heard in the speaker when this change is made. By adjustingthe two potentiometers 21 and 28 in regard to the strength of the twolight sources acting on the photo-electric cells in the two machines andthe quality of the film used, it is possible to make this change-overwithout any increase or decrease in the volume of sound at all. Whenusing our automatic change-over the audience observing the movingpicture will not be able to tell when a change-over is being made.

As has been heretofore stated, it is possible to make this change-overentirely automatic, controlling it by the amount of film run through themachines. One method of doing this, we have shown and illustrated in thedrawings. It is, of course, to be understood that when we referred tothe first machine and the second machine, we merely used thisphraseology for the purpose of illustration, since it makes nodifference whatever which machine is used as the first machine. Theprocedure will be to load one machine with the first reel to be shown,and the other machine with the succeeding reel. When the film has runout on the first machine, the change-over will be made to the secondmachine. The first machine is now loaded with the third reel, and whenthe film on the second machine is run, the change-over will be made backto the first machine, and so on, going back and forth between the twomachines. It may be desirable to use more than two machines, and it willbe apparent that our invention will work just as well with any number ofmachines; therefore we do not wish to limit ourselves to our inventionas applied to only two machines.

It is to be understood that different forms of our preferred form may bemade without departing from the spirit of our invention.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent, is:-

l. A sound change-over for motion picture projectors comprising twosolenoids with their cores in line with each other, an armature commonto both solenoids and slidably journaled in their cores, a collar onsaid armature, two switches comprising a coiled spring urged against acontact positioned above said armature and in such position that thecollar will alternately lift the springs from their contacts when thearmature is slid in one direction or the other, the two springs beingconnected to a loud speaker unit and the contacts being connected to thesound output terminal of two projectors, and means for energizing eachsolenoid separately so as to shift the armature from one side to theother.

2. A sound change-over for motion picture projectors comprising twosolenoids with their cores in line with each other, an armature commonto both solenoids and slidably journaled in their cores, a collar onsaid armature, two switches comprising a coiled spring urged against acontact positioned above said armature and in such position that thecollar will alternately lift the springs from their contacts when thearmature is slid in one direction or the other, the two springs beingconnected to a loud speaker unit and the contacts being connected to thesound output terminal of two projectors, and means for energizing eachsolenoid separately so as to shift the armature from one side to theother, said energizing means actuated by the amount of film on theloading reel in the two projectors.

3. Asound change-over for motion picture projectors comprising twosolenoids with their cores in line with each other, an armature commonto both solenoids and slidably journaled in their cores, a collar onsaid armature, two switches comprising a coiled spring urged against acontact positioned above said armature and in such position that thecollar will alternately lift the springs from their contacts when thearmature is slid in one direction or the other, the two springs beingconnected to a loud speaker unit and the contacts being connected to thesound output terminal of two projectors, means for energizing eachsolenoid separately so as to shift the armature from one side to theother, and a grid leak connected between the contacts and the ground, soas to eliminate any outside noise when the contacts are made. andbroken.

4. In a sound changeover for motion picture projection comprising aspeaker and at least two sound projectors alternately electricallyconnected to said speaker, said electrical connection of said projectorsto said speaker being permanently grounded through a very highresistance.

5. In a sound changeover for motion picture projection consisting of aspeaker unit and at least two sound projector units having electricalconnections adapted to be alternately connected to said speaker, saidelectrical connections being permanently grounded through a very highresistance.

6. In a motion picture sound projector having an electrical connectionto a speaker, said electrical connection being grounded through a veryhigh resistance to eliminate extraneous noise in said speaker when saidelectrical connection is broken and made.

ANDREW V. MULLEN. JOHN C. SMITH.

